Chronic Obstructive Pulmonary Disease

BASICS

DESCRIPTION

Chronic obstructive pulmonary disease encompasses several diffuse pulmonary diseases including chronic bronchitis, asthma, cystic fibrosis, bronchiectasis, and emphysema. The term usually refers to a mixture of chronic bronchitis and emphysema.

Chronic bronchitis is defined clinically by increased mucus production and recurrent cough present on most days for at least three months during at least two consecutive years.
Emphysema is the destruction of interalveolar septa. The disease occurs in the distal or terminal airways and involves both airways and lung parenchyma.
System(s) affected: Pulmonary
Genetics:
- Chronic bronchitis is not a genetic disorder although some studies have hinted at a predisposition for development of this condition.
- A rare form of emphysema, antiprotease deficiency (due to alpha 1-antitrypsin deficiency), is an inherited disorder that is an expression of two autosomal codominant alleles.
Incidence/Prevalence in USA:
- 10-20% of adults; more than 60,000 deaths/year
- 8 million people have chronic bronchitis; 2 million people have emphysema
Predominant age: Over 40 years
Predominant sex: Male > Female

SIGNS AND SYMPTOMS

Chronic bronchitis
- Cough
- Sputum production
- Frequent infections
- Intermittent dyspnea
- Pedal edema
- Plethora
- Cyanosis
- Wheezing
- Weight gain
- Diminished breath sounds
Emphysema
- Minimal cough
- Scant sputum
- Dyspnea
- Often significant weight loss
- Occasional infections
- Barrel chest
- Minimal wheezing
- Use of accessory muscles of respiration
- Pursed lip breathing
- Cyanosis is slight or absent
- Chronic obstructive pulmonary disease & emphysema

CAUSES

Cigarette smoking
Air pollution
Antiprotease deficiency
Occupational exposure (i.e., firefighters)
Infection possibly (viral)

RISK FACTORS

Passive smoking (especially adults whose parents smoked)
Severe viral pneumonia early in life
Aging
Ethyl alcohol (EtOH) consumption
Airway hyperactivity

DIAGNOSIS

LABORATORY

Chronic bronchitis
- Hypercapnia
- Polycythemia
- Hypoxia can be moderate to severe
Emphysema
- Normal serum hemoglobin or polycythemia
- Normal PaCO2; unless FEV1 < 1 L/sec, then can be elevated
- Mild hypoxia

Drugs that may alter lab results: Sedatives including alcohol
Disorders that may alter lab results: Obesity, concurrent restrictive lung dysfunction, primary pulmonary hypertension, acute infections, anemia, pulmonary embolism sleep apnea, congestive heart failure

PATHOLOGICAL FINDINGS

Chronic bronchitis
- Bronchial mucous gland enlargement
- Increased number of secretory cells in surface epithelium
- Thickened small airways from edema and inflammation
- Smooth muscle hyperplasia
- Mucus plugging
- Bacterial colonization of airways
Emphysema
- Entire lung affected
- Bronchi usually clear of secretions
- Anthracotic pigment
- Alveoli enlarged with loss of septa
- Cartilage atrophy
- Bullae

SPECIAL TESTS

Pulmonary function testing
- Decreased FEV1 with concomitant reduction in FEV1/FVC ratio
- Poor or absent reversibility to bronchodilators
- FVC may be normal or reduced
- Normal or increased total lung capacity
- Increased residual volume
- Diffusing capacity is normal or reduced
Nocturnal oximetry

IMAGING

Chronic bronchitis chest x-ray shows increased bronchovascular markings and cardiomegaly
Emphysema chest x-ray shows small heart, hyperinflation, flat diaphragms and possibly bullous changes
CAT scan may show bullous changes

DIAGNOSTIC PROCEDURES

Pulmonary function tests
ABGs
Chest x-ray

TREATMENT

APPROPRIATE HEALTH CARE

Outpatient treatment is usually adequate. However, hospitalization may be required for exacerbation, infection, or diagnostic procedures (i.e., transbronchial lung biopsy).
Acute respiratory failure may require an intensive care unit and possibly a mechanical ventilator to support the patient

GENERAL MEASURES

Smoking cessation
Aggressive treatment of infections
Treat any reversible bronchospasm
Reduction of secretions through good pulmonary hygiene
Cor pulmonale may necessitate use of home oxygen
Pulmonary rehabilitation
Appropriate vaccinations
Adequate hydration

SURGICAL MEASURES

Lung reduction surgery (selected cases)
Lung transplantation (selected cases)

ACTIVITY

As tolerated. Full activity should be encouraged.

DIET

A well balanced, high protein diet is suggested. Low carbohydrates may benefit those with hypercarbia.

PATIENT EDUCATION

Printed material is available from the National Jewish Hospital in Denver, Colorado. The local branch of the American Lung Association also has educational material.
Coach patients in pulmonary rehabilitation

FOLLOW UP

PREVENTION/AVOIDANCE

Avoidance of smoking is the most important preventive measure. Passive smoke also has been shown to be harmful.

POSSIBLE COMPLICATIONS

Infection is common
Cor pulmonale, secondary polycythemia, bullous lung disease, acute or chronic respiratory failure, pulmonary hypertension, malnutrition, pneumothorax

EXPECTED COURSE AND PROGNOSIS

The patient's age and post-bronchodilator forced expiratory volume (FEV1) are the most important predictors of prognosis. Young age and FEV1 > 50% predicted have a good prognosis. Older patients with more severe lung disease do worse.
Supplemental oxygen, when indicated, has been shown to increase survival
Smoking cessation is also important for an improved prognosis
Malnutrition, cor pulmonale, hypercapnia and pulse > 100 indicate a poor prognosis

MISCELLANEOUS

ASSOCIATED CONDITIONS

Lung cancer
Coronary artery disease
Peptic ulcer disease
Chronic sinusitis
Malnutrition
Laryngeal carcinoma

AGE-RELATED FACTORS

Pediatric: Repeated childhood respiratory illnesses make COPD a greater risk
Geriatric: Relative risk is 1.2 to 2.3 times greater than in younger person
Others: Unusual under age 25 unless antiprotease deficiency is present. Incidence increases as age approaches 60.

PREGNANCY

N/A

OTHER NOTES

Albuterol is also known as salbutamol
Other important considerations for treatment include adequate hydration, supplemental oxygen, antibiotics when indicated, mucolytic agents, pulmonary rehabilitation, good pulmonary hygiene

ABBREVIATIONS

FVC = forced vital capacity
FEV1 = forced expiratory volume at 1 second
COPD = chronic obstructive pulmonary disease
ABG = arterial blood gases

Clinical Investigations

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